Reference
Only
Manitowoc
Published 09-09-16, Control # 229-09
5-3
MLC650 SERVICE/MAINTENANCE MANUAL
HOISTS
5
55
Drum 1 Lowering Operation
for the following.
To enable the drum 1 pumps and motors, the switches listed
below must be in the stated positions:
•
Seat safety switch closed
•
Drum 1 park switch in the OFF position
NOTE:
For the following operation, the drum 6 park switch
and/or left travel park switch are in the ON position.
In the default state, the CCM-10 control module de-
energizes the drum 1/drum 6 selector solenoid valve (3),
located in the accessory valve manifold (1). The de-
energized solenoid valve routes hydraulic fluid to the pilot
control of drum 1/drum 6 diverter valve (10). The diverter
valve shifts to the default position, allowing main hydraulic
fluid from the pump 1 to flow to the double manifold (11),
then to the left and right hydraulic motors (14 and 16).
During the drum 1 lowering operation when the drum 6 park
switch and/or left travel park switch are in the ON position,
the CCM-10 control module energizes the left travel/drum 1
selector solenoid valve (2), located in the accessory valve
manifold. The energized solenoid valve routes hydraulic fluid
to the pilot control of the left travel/drum 1 diverter valve (9).
The diverter valve shifts position, allowing the main hydraulic
fluid from pump 3 to flow to the double manifold where it can
combine with the fluid from the pump 1. The combined fluid
then flows to the left and right hydraulic motors.
Hydraulic fluid from the left travel/drum 1 selector solenoid
valve also flows to the pilot control of the pump 3 charge
pressure diverter valve (4), causing the valve to shift. When
in this position, charge pressure from pump 3 is blocked.
Only pump 1 charge pressure is available to the charge
pressure check valve (13). If the main pump pressure drops
below a predetermined level, the check valve opens,
allowing the pump 1 charge pressure hydraulic fluid into the
main pressure circuit as makeup oil.
During the drum 1 lowering operation, the CCM-10 control
module sends a signal to the IOLC32 control module via the
CAN Bus to ramp up the PWM duty cycle to the B-side
solenoids of pumps 1 and/or 3 EDCs. The PWM signal is in
proportion to the speed commanded by the joystick.
Increasing the PWM duty cycle increases the pump
swashplate angle, which increases the hydraulic flow from
the B-side of the pump(s). From the pump(s), the flow is
routed through the diverter valves (9 and 10), the double
manifold (11), and then into the A-side of the right hydraulic
motor (16) and the B-side of the left hydraulic motor (14).
The CCM-10 control module sends a signal to the CCMC11
control module via the CAN Bus to ramp up the PWM duty
cycle to the left motor and right motor controllers. Increasing
the PWM duty cycle decreases the swashplate angle in each
motor, which increases the motor flow until the rotational
speed is maximized based on the pump flow.
The drum 1 motor speed sensor, pump 1 pressure
transducer (drum 1 psi) (7), and pump 3 pressure transducer
(L-travel psi) (5) provide closed loop feedback to the control
modules. The control algorithm uses this feedback to adjust
the pump and motor flows, while maintaining the speeds
commanded by the joystick input.
Drum 1 Minimum Bail Limit
The optional minimum bail limit assembly on drum 1 is a
protective device that limits how much wire rope can be
spooled off the drum.
The minimum bail limit automatically stops the drum when
there are three to four wraps of wire rope remaining on the
first layer.
When the limit is reached, the operating limit
fault is activated and the fault icon appears in
the fault bar of the main display working
screen.
NOTE:
The drum can be operated in the hoist direction
when the minimum bail limit switch is contacted.
Field adjustment should not be necessary unless a new limit
switch is installed.
for the following instructions.
Limit Switch Replacement
Removal
1.
Land the load from the drum being adjusted.
2.
Lockout-tagout the crane.
3.
Remove the screws (7) and the limit switch (8).
4.
Remove the limit switch cover (9).
5.
Disconnect the electrical wires, including the jumper
wire, inside the limit switch (see View C).
6.
Remove the cable restraint connector (10) and carefully
pull the electrical cable and wires from the limit switch.
WARNING
Falling Load Hazard!
Avoid possible injury. Do not operate the drum with less
than three or four full wraps of wire rope remaining on the
drum. Doing so can cause the wire rope to be pulled out of
the drum and the load to fall.
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